QSqlIndex Class

The QSqlIndex class provides functions to manipulate and describe database indexes. 更多...

头：	#include <QSqlIndex>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Sql) target_link_libraries(mytarget PRIVATE Qt6::Sql)
qmake:	QT += sql
继承：	QSqlRecord

所有成员列表，包括继承成员
QSqlIndex is part of 数据库类 .

公共函数

	QSqlIndex (const QString & cursorname = QString(), const QString & name = QString())
	QSqlIndex (const QSqlIndex & other )
`(从 6.6 起)`	QSqlIndex (QSqlIndex && other )
	~QSqlIndex ()
void	append (const QSqlField & field )
void	append (const QSqlField & field , bool desc )
QString	cursorName () const
bool	isDescending (int i ) const
QString	name () const
void	setCursorName (const QString & cursorName )
void	setDescending (int i , bool desc )
void	setName (const QString & name )
QSqlIndex &	operator= (const QSqlIndex & other )
`(从 6.6 起)` QSqlIndex &	operator= (QSqlIndex && other )

详细描述

An index refers to a single table or view in a database. Information about the fields that comprise the index can be used to generate SQL statements.

成员函数文档编制

`[explicit]` QSqlIndex:: QSqlIndex (const QString & cursorname = QString(), const QString & name = QString())

Constructs an empty index using the cursor name cursorname and index name name .

QSqlIndex:: QSqlIndex (const QSqlIndex & other )

构造副本为 other .

`[noexcept, since 6.6]` QSqlIndex:: QSqlIndex ( QSqlIndex && other )

Move-constructs a new QSqlIndex from other .

注意： The moved-from object other is placed in a partially-formed state, in which the only valid operations are destruction and assignment of a new value.

该函数在 Qt 6.6 引入。

`[noexcept]` QSqlIndex:: ~QSqlIndex ()

销毁对象并释放任何分配资源。

void QSqlIndex:: append (const QSqlField & field )

Appends the field field to the list of indexed fields. The field is appended with an ascending sort order.

void QSqlIndex:: append (const QSqlField & field , bool desc )

这是重载函数。

Appends the field field to the list of indexed fields. The field is appended with an ascending sort order, unless desc 为 true。

QString QSqlIndex:: cursorName () const

Returns the name of the cursor which the index is associated with.

另请参阅 setCursorName ().

bool QSqlIndex:: isDescending ( int i ) const

返回 true if field i in the index is sorted in descending order; otherwise returns false .

QString QSqlIndex:: name () const

Returns the name of the index.

另请参阅 setName ().

void QSqlIndex:: setCursorName (const QString & cursorName )

Sets the name of the cursor that the index is associated with to cursorName .

另请参阅 cursorName ().

void QSqlIndex:: setDescending ( int i , bool desc )

若 desc is true, field i is sorted in descending order. Otherwise, field i is sorted in ascending order (the default). If the field does not exist, nothing happens.

另请参阅 isDescending ().

void QSqlIndex:: setName (const QString & name )

Sets the name of the index to name .

另请参阅 name ().

QSqlIndex &QSqlIndex:: operator= (const QSqlIndex & other )

Sets the index equal to other .

`[noexcept, since 6.6]` QSqlIndex &QSqlIndex:: operator= ( QSqlIndex && other )

移动赋值 other 到此 QSqlIndex 实例。